This invention relates to a method for treating hays, grains, and silages, and more particularly an improved method for preventing microbial growth and spoilage of feedgrains and hays, for detoxifying aflatoxins in grains, and for increasing the lactic acid content in silages to improve their fermentation.
As of this writing, the United States Food and Drug Administration prevents interstate shipment of or use in animal feeds of grains containing more than 20 parts per billion (ppb) of aflatoxin B.sub.1. Thus, if grain containing more than 20 ppb of aflatoxin B.sub.1 could be detoxified to contain less than 20 ppb of aflatoxin B.sub.1, then this grain could be put to productive use.
It is desireable to harvest hay with sufficient moisture to prevent leaf shattering during the harvesting. This is because much of the nutrient value of the hay is contained in the leaves, and the harvesting of dry hay results in the destruction and loss of the leaves during the harvesting process. However, storing large quantities (on the order of several tons) of high moisture hay (greater than 22% moisture by weight of the hay) normally results in heating and production of mold within two weeks after storage. The growth of this mold substantially reduces the feed value of the hay and can be toxic to livestock. Thus, a method of retarding the heating and mold formation of this type of high moisture forage is desireable.
Lactic acid production is generally accepted as an accurate measure of the success of the anaerobic fermentation process of silage. Thus, it is desireable to increase the degree of fermentation of silage. Such increase is evidenced by an increased lactic acid content.
Animal feeds such as grains, hays, and silages have been exposed to anhydrous gaseous ammonia for the purposes of controlling microbial growth and spoilage, detoxifying aflatoxins, and increasing fermentation in silages. Regarding the effect of gaseous anhydrous ammonia (NH.sub.3) on dry and high moisture (HM) coastal Bermudagrass hay, see Cross et al., "Effect of Moisture Level and Injection of Ammonia on Nutrient Quality and Preservation of Coastal Bermudagrass Hay," Journal of Animal Science. Volume 61, No. 6, pages 1370-1377 (1985); and Cross et al., "Effect of Ammonia Level and Time of Exposure to Ammonia on Nutritional and Preservatory Characteristics of Dry and High-Moisture Coastal Bermudagrass Hay," Animal Feed Science and Technology, Elsevier Science Publishers B. V., Amsterdam, Volume 14, pages 55-65 (1986). It has been known prior to the invention that the exposure to gaseous ammonia can be effected within a substantially gas tight enclosure, such as a silo or a plastic sheeting. However, gaseous ammonia is both costly and dangerous to the farmers who must store and use it.
U.S. Pat. No. 4,426,396 to Young discloses a method for treating animal feed stuffs destined for storage. The Young method employs a solution of urea, ammonia, and urea polymers such as biuret, triuret, cyanuric acid, and urea cyanurate to effect a chemical release of gaseous ammonia over time. It is believed that the urease enzyme causes the urea polymers to decompose slowly. This gradual decomposition caused by the urease enzyme sustains the presence of ammonia for a period of time beyond the decomposition of the initially present urea. However, the urease enzyme is costly, and the rate at which ammonia is released cannot be reliably predicted.